Recently, several recording apparatuses which digitally record and reproduce digitalized video and audio signals have been put to practical use or proposed. Hereinafter, an example of such conventional digital recording apparatuses will be described with reference to the drawings.
FIG. 11 is a block diagram of a conventional digital recording apparatus. In FIG. 11, 1 denotes an input terminal, 40 denotes an error correcting encoder, and 41 denotes a modulator. The reference numeral 43 denotes a rate information extractor, 44 denotes a system controller, and 39 denotes a tape feed controller. The reference numeral 8 denotes a tape-like recording medium, and 42 denotes recording heads.
The operation of the thus configured digital recording apparatus will now be described.
A digital bit stream signal of an image, a voice, or a data is input through the input terminal 1. The error correcting encoder 40 adds an error correcting code which compensates a data error caused by record/reproduction, to the digital signal input through the input terminal 1, and converts the signal into a recording format for a recording apparatus to produce an original recording signal.
The rate information extractor 43 acquires data rate information from the input bit stream, and the system controller 44 changes the recording rate in accordance with the rate to control the error correcting encoder 40 and the tape feed controller 39. For example, the rate information is that which is described in an input bit stream by a broadcasting station or the like and then transmitted. For example, the maximum rate of the bit stream is described.
The modulator 41 applies modulation for recording on the recording signal which is produced by the error correcting encoder 40. The recording heads 42 record the modulated recording signal on the tape-like recording medium 8. In this way, the conventional digital recording apparatus is configured so as to extract rate information from an input bit stream and record the input bit stream in a preset recording mode. The above-mentioned digital recording apparatus is disclosed in, for example, Japanese Patent Publication (Kokai) No. HEI08111068. The entire disclosure of Japanese Patent Publication (Kokai) No. HEI08111068 is incorporated herein by reference in its entirety.
However, the above-mentioned configuration has problems in that, in a case such as that where the rate information is not added to the input bit stream, where the accuracy of the rate information is low, where the rate information is different from that related to a time period about which the recording apparatus wishes to know the rate, or where the input bit stream contains a plurality of streams, the recording mode cannot be determined or the input bit stream cannot be recorded in the preset recording mode because the recording data rate is not known or is incorrect, the data amount per record unit in the recording apparatus is not known, or the calculation of the total rate of the recording streams requires a long time period.
When the recording mode cannot be determined, even in the case where the rate of the input bit stream is large, data must be set so as to be recorded on the tape-like recording medium 8 without omission. As a result, the input bit stream is recorded on the tape-like recording medium 8 in a recording mode which corresponds to such a case of a large rate. Even in the case where the rate is small in practice, when the rate of the input bit stream is not known, therefore, the bit stream is recorded by using a recording mode for the case of a large rate, and hence the tape cannot be efficiently used.